AMS-02 will be the first large magnetic spectrometer to be used in space. The designers have therefore been presented with a number of unique challenges, especially in designing a magnetic system capable of operating safely and for a long time in space.
Two magnetic systems have been developed by the AMS Collaboration:
– A Permanent Magnet operating at ambient temperature and built with 6,000 Ne-Fe-B pieces carefully magnetized and assembled together. This magnet was successfully flown in 1998 on the STS91 mission.
– A Super-Conducting Magnet operating at 1.8 degrees above absolute zero (0 K), built with 14 coils of superconducting Niobium wire stabilized in an Aluminum matrix. This magnet operates at 400 A and requires continuous refrigeration by slow evaporation of 2,500 liters of superfluid Helium to maintain the low temperature. After many years of development the superconducting magnet will be tested at ESA-ESTEC during April 2010 in the large space simulator at the Nordwijk ESA center.
Both magnetic systems share the same field configuration, the so called magic ring, ensuring that the magnet has a negligible net dipole moment so as to avoid coupling with the Earth magnetic field which would disturb the orbit of the ISS. They also have identical mechanical dimensions and interfaces with the detector subsystems of the AMS experiment.
Because of the high levels of radiation in space, AMS Electronics is also particularly challenging, its over 600 separate computers use special radiation-tolerant chips, developed for high energy physics, which are ~ 10 times as fast as typical spaceflight computers.
For an overview of each of AMS-02 sub-systems, follow the links below:
Magnet bends in opposite directions charged particles/antiparticles
Transition Radiation Detector (TRD) identifies electrons and positrons among other cosmic-rays
Time-of-Flight System (ToF) warns the sub-detectors of incoming cosmic-rays
Silicon Tracker (Tracker) detects the particle charge sign, separating matter from antimatter
Ring-Imaging Cherenkov Detector (RICH) measures with high precision the velocity of cosmic-rays
Electromagnetic Calorimeter (ECAL) measures energy of incoming electrons, positrons and γ-rays
Anti-Coincidence Counter (ACC) rejects cosmic rays traversing the magnet walls
Tracker Alignment System (TAS) checks the Tracker alignment stability
Star Tracker and GPS defines the position and orientation of the AMS-02 experiment
Electronics transform the signals detected by the various particle detectors into digital information to be analyzed by computers